A touch screen is an input device that allows for inputting of a user's instructions by the user directly clicking the icons displayed on the screen of an image display with his/her finger or an object. When touched by the user with his/her finger or the object, the touch screen detects the touch points and drives the liquid crystal display according to the command corresponding to the clicked icon to achieve a specific display.
Depending upon their implementation principles, the existing touch screens are mainly of either capacitive types or electromagnetic types. The capacitive touch screen recognizes a touch operation via the received touch signals (i.e., electrical signals), and the electromagnetic touch screen recognizes a touch operation via the received touch signals (i.e., electromagnetic signals). Among the capacitive touch screens, taking the self-capacitance touch screen as an example, detection of a position touched by a finger is achieved based on the principle of the self-capacitance, which can be specified as follows: with a plurality of self-capacitance electrodes arranged in the same layer and independent from each other in a touch screen, when the screen is not touched by the human body, the individual self-capacitance electrodes subject to a fixed capacitance, and when the screen is touched by the human body, the self-capacitance electrodes corresponding to the touch position subject to a fixed capacitance plus the capacitance of the human body; thus, the touch position can be determined by a touch detection chip detecting the variation in the capacitance value of the individual self-capacitance electrodes during the touch period of time. In a specific implementation, the number of the self-capacitance electrodes is simply huge. Assuming that each self-capacitance electrode occupies an area of 5 mm*5 mm, by way of example, then 264 self-capacitance electrodes are needed in a liquid crystal display of 5-inch. With the self-capacitance electrodes designed to be even smaller, more of them will be needed, resulting in a great number of wires connected to the self-capacitance electrodes.
Therefore, existence of numerous electrodes and wires in the prior art touch screen leads to a complicated apparatus.